The invention relates generally to apparatus for carrying out a process that uses supercritical fluids, such as, for example, a process for preparing coating materials as described in U.S. Pat. No. 5,399,597 and co-pending U.S. patent application Ser. No. 08/438,681 entitled "CONTROL SYSTEM FOR PROCESSES USING SUPERCRITICAL FLUID", the entire disclosures of which are both fully incorporated herein by reference. More specifically, the invention relates to improvements and alternative embodiments of the mixing system including the pressure vessel and agitator that are part of the overall system described in the aforementioned disclosures.
The systems described in the referenced disclosures are effective for many processes that use supercritical fluids. However, improvements in the pressure vessel (reactor tank) have been discovered which can significantly improve the overall performance and quality of the finished product for different reaction processes.
Temperature control within the pressure vessel (also referred to herein as the reactor vessel or tank) is an important part of the overall reaction process. It is especially important to provide a heat transfer system that can rapidly control changes of the reaction mixture within the pressure vessel. Although conventional heat/cool jackets can be used, as described in the referenced disclosures, some reaction processes may require a higher degree of control of temperature within the pressure vessel. This is particularly so for effecting and/or controlling rapid changes in temperature and pressure within the pressure vessel.
The agitator is also an important element of the overall system. The agitator not only is used for mixing the batch ingredients during the reaction process in the pressure vessel, but is also used for delivery or transfer of the finished reaction to the receiver vessel. Typical reaction processes can involve high viscosity slurries within the pressure vessel which conventional agitators may be inadequate to either mix or assist in the transfer of the finished reaction to the receiver.
The objectives exist, therefore, to provide a mixing system that improves the flexibility and utility of supercritical process systems as such as are described in the aforementioned disclosures.